1. Field of the Invention
The present invention relates to a hydrostatic and a hydrostatic/hydrodynamic air bearing in which the bearing is damped by a porous metal sleeve encircling the journal.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
A prior art hydrostatic air bearing is shown in FIGS. 1 and 2, while a prior art hydrostatic/hydrodynamic air bearing is shown in FIGS. 3 and 4. The prior art hydrostatic air bearing includes a solid sleeve 20 encircling the journal 12 and being rotated with the journal in the bearing both at a rotational velocity and direction of ω. A bearing fluid like air is pumped into the bearing assembly through passages 18 in the bearing race 14, the passages opening into a pressure dam 16 on the inner surface of a cavity 17 formed within the bearing race 14. The pressure of the bearing fluid is highest in the space having the shortest distance between the solid metal sleeve 20 and the bearing race 14. In FIG. 1, the highest pressure would be at the cutout portion located at the 6 o'clock position. The higher pressure bearing fluid flows from the higher pressure side to the lower pressure side, which in the case of the prior art FIG. 1 bearing is around the solid metal sleeve 20 toward the top cutout. In this prior art bearing, the bearing fluid is not restricted in the flow path from one side of the journal to the opposite side.
A prior art hydrostatic/hydrodynamic air bearing is shown in FIGS. 3 and 4 in which the solid metal sleeve 20 in FIGS. 1 and 2 is not secured on the journal, but is an annular sleeve that does not rotate with the journal 12 and includes a space 19 between the journal 12 and the metal sleeve 30. The bearing fluid flow is the same in FIGS. 3 and 4 and is FIGS. 1 and 2, in that the bearing fluid flows around the outer surface of the metal sleeve 30.